Williams.] 82 [April 20, 
Tt differs from the genus Heaacrinus Austin, as generally understood, in 
possessing a well defined third primary radial similar in size to the second, 
and from which the free arms abruptly diverge. 
In respect of one character it differs fundamentally from all the known 
representations of the genus, section or family ; and, in fact, from all 
hitherto described Orinoids, in the possession of slender, acicular spines 
which were free from the plates, and were evidently articulated by some 
means upon elevated pitted tubercles on the surface of the plates of the 
calyx, vault and free arms. 
We find so-called spines on a few Crinoids, on the plates of the vault in 
the genera Dorycrinus and Amphoracocrinus, and upon the calyx plates 
of Rhodocrinus and other genera. 
Tn all these cases, however, the ‘‘spines’’ or tubercles consist merely of 
thorn-like expansions of the plates, and, so far as T can learn, there is no 
recorded evidence of the occurrence upon any true Crinoid, of free spines 
articulated to the plates as in the Echinoids, 
In the absence of the spines themselves, the low rounded tubercles, 
pitted at the apex, suggest resemblance to the mamelon of the Hehinoids, 
but in the specimens herein described, the spines as well as the tubercles 
are represented. 
Other specimens have been examined in which the pitted tubercles 
alone are seen; the spines have been found in only a single locality, but 
there upon several individuals. 
These specimens, like most of the fossils of the fine sandy shales of the 
upper Devonian, are in the condition of hollow impressions preserving 
scarcely a particle of the original substance of the test, but the impressions 
are beautifully perfect, showing the finest details of surface marking and 
configuration. On the impressions of some of the slender spines, fine 
longitudinal strie, invisible to the naked eye, are distinctly seen with a 
good lens. 
Palontologists accustomed to throw aside these hollow impressions of 
fossils in the Chemung rocks, as poor and worthless specimens, will be 
surprised at the perfection in which all the surface details, external and in- 
ternal are preserved. 
Many minute characters are visible in such specimens that are rarely seen 
in so called perfect specimens from limestone rocks, where the immediate 
surface is very generally removed in taking the fossil from the matrix. 
In the present case the specimens break along the cavities from which 
the test has been dissolved, the inner and outer surfaces of the plates both 
appearing, and the spines in place. That they were true spines, and not 
prolongations of the plate surface is evidenced by the fact that the spines, 
though in place, like bristles radiating from the surface, are in no case en- 
tirely continuous with the impressions left by the removal of the plate ; 
there is always a thin film of matrix separating the base of the spine from 
the apex of the tubercles, to which in several cases they are closely ap- 
proximate. 
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